What's the output when you run pip3 install -r requirements.txt ?
pip3:
pip3 install -r requirements.txt
Traceback (most recent call last):
File "/usr/bin/pip3", line 9, in
from pip import main
ImportError: cannot import name 'main'
Did you upgrade pip3 outside of your distributions package manager (i.e. using pip3 --upgrade) ?
That's not really recommended.
If you however still want to use the up-do-date (and not supported by your OS) version of pip, try it with the following command:
python3 -m pip install -r requirements.txt